1. Field of the Invention
The present invention relates to an optical device having an image-stabilizing insertable/removable optical element which can be moved to correct image shake and removed to a position outside an anti-shake driving range of the optical element.
2. Description of the Related Art
Optical devices such as cameras which are equipped with an anti-shake mechanism (image shake correcting mechanism/image stabilizing mechanism) that moves a specific optical element such as a lens element or an image sensor (image pickup device) in a plane orthogonal to an optical axis of an optical system to reduce (correct) image shake are known in the art. In Japanese Unexamined Patent Publication 2007-163961, a technique for removing (radially retracting) an image-stabilizing optical element to a position outside an anti-shake driving range (to a position off an optical axis of the optical system) when an optical device that incorporates the anti-shake mechanism moves from an operating state to a lens barrel accommodated state (fully retracted state/non-operating state) in which no pictures are taken, has been proposed for the purpose of making a lens barrel compact in size.
In the lens barrel disclosed in the aforementioned Japanese Unexamined Patent Publication, an insertable/removable frame which supports, at its free end, an image shake correcting lens group (correcting lens group/image-stabilizing insertable/removable optical element) is pivoted at a frame member (anti-shake frame) which is driven in a plane orthogonal to an optical axis to reduce image shake. The insertable/removable frame is rotated so as to make the optical axis of the image shake correcting lens group coincide with the optical axis of the other optical elements (lens groups) when the lens barrel moves from the lens barrel accommodated state to a ready-to-photograph state, and the insertable/removable frame is rotated so as to remove the image shake correcting lens group from the optical axis of the other optical elements when the lens barrel moves from a ready-to-photograph state to the lens barrel accommodated state. A clearance hole (specifically a clearance hole which includes a circular arc groove about the center of rotation of the anti-shake frame) which allows the image shake correcting lens group to move is formed in the anti-shake frame.
In optical devices having such an image-stabilizing insertable/removable optical element, it is desirable that the anti-shake frame and the elements installed thereon (specifically the insertable/removable frame and the image shake correcting lens group) be as light-weight as possible so that the anti-shake driving operation can be performed smoothly. In addition, it is desirable that the diameter and the wall thickness of the anti-shake frame be as small as possible to reduce the size (diameter) and thickness of the whole optical device. However, since the insertable/removable frame is pivotally supported by the anti-shake frame and also since the aforementioned clearance hole is formed in the anti-shake frame, if the anti-shake frame is excessively made small in diameter and thickness, the strength of the anti-shake frame becomes poor, which may deteriorate the positional accuracy of the image shake correcting lens group, especially when in a ready-to-photograph position.